Technical Field
The present invention relates to a fuel cell stack configured by stacking a plurality of fuel cells and a fuel cell system having the fuel cell stack.
Related Art
A fuel cell is formed by interposing an electrolyte membrane between an anode and a cathode. The fuel cell generates electric power using a hydrogen-containing anode gas supplied to the anode and an oxygen-containing cathode gas supplied to the cathode. An electrochemical reaction occurring between the anode and the cathode can be expressed as follows.Anode: 2H2→4H++4e−  (1)Cathode: 4H++4e−+O2→2H2O  (2)
Through the electrochemical reactions (1) and (2), the fuel cell generates an electromotive force of approximately 1 V.
When such a fuel cell is employed in a vehicle power supply system, several hundreds of fuel cells are stacked and used in the form of a fuel cell stack because a vehicle consumes large power. In addition, a fuel cell system is provided to supply the fuel cell stack with an anode gas and a cathode gas so that power for driving a vehicle is extracted.
In JP 2006-66131 A, there is discussed a fuel cell stack having an internal manifold as a path for flowing the anode gas or the cathode gas. Such an internal manifold is provided as a path by connecting through-holes formed in the fuel cell in a fuel-cell stacking direction.
Produced water produced at the time of power generation and the like flows to a discharge-side internal manifold for discharging the anode gas and the cathode gas to the outside of the fuel cell stack. As the produced water stays in the inside of the discharge-side internal manifold and returns to a reaction surface (active area), power generation performance of the fuel cell stack is degraded. For this reason, the discharge-side internal manifold is preferably configured to easily discharge the produced water.